1. Field of the Invention
The present invention relates to a communication system.
2. Description of the Related Art
Telecommunications networks typically operate in accordance with a given standard or specification which sets out what the various elements of the network are permitted to do and how that should be achieved. For example, the standard or specification may define whether the user, or more precisely, user equipment or terminal is provided with circuit switched and/or packet switched service. The standard or specification may also define the communication protocols and/or parameters which shall be used for the connection. In other words, the standards and/or specifications define the “rules” on which the communication can be based. Examples of the different standards and/or specifications for wireless communication include, without limiting to these, specifications such as GSM (Global System for Mobile communications) or various GSM based systems (such as GPRS: General Packet Radio Service), AMPS (American Mobile Phone System), DAMPS (Digital AMPS), WCDMA (Wideband Code Division Multiple Access) or TD/CDMA in UMTS (Time Division/Code Division Multiple Access in Universal Mobile Telecommunications System), IMT 2000 and so on.
In known wireless telecommunications systems such as GSM, GPRS and the proposed third generation system UMTS, a user can pay for calls and services in one of two ways. Firstly, the user is billed for the calls and services that the user has used or made. This occurs after the user has made the call or used the service. Secondly, the user makes a payment in advance. As the user makes calls or uses service, the amount held on account is reduced. The user can top up or replenish the account in various different ways.
In the pay in advance environment (sometimes referred to as pay-as-you go or pre-payment), an entity is provided which stores the amount of money which the user currently has left. As the user makes calls or uses services, the stored amount is debited by the amount used. In some systems, when a user starts to make a call or use a service, a given amount of the stored amount is reserved for the service. If necessary, it is possible to reserve further amounts. When a call or service is completed, any unused portion of the reserved amount is returned to the stored amount. The stored amount is thus updated to reflect the amount of money used.
However, the issue of how to deal with access to a number of different services in a single session in the context of a prepaid environment has not been addressed.
Another problem is that the entity responsible for storing the amount used may in some UMTS systems use the CAMEL (Customized Applications for Mobile Network Enhanced Logic) protocol. However this protocol cannot handle monetary amounts.
A further problem is that the amount of communication with the entity responsible for charging should be kept to a minimum. If the signaling is not minimized the capacity of this entity would need to be increased. This would increase the cost of the entity, which is in any event costly. In any case minimizing signaling is always desirable.
A further problem relates to the reservation of an amount. If too small an amount is reserved, then the amount of signaling required is increased. If too large an amount is reserved, then the user may not have enough money for anything else or even enough money for the reservation.